This proposal requests a small animal ultrasound imaging system to replace one with technology dating to 2002. The machine requested is a VisualSonics 2100 imaging system which has a new design compared to the older terminal technology. It is based on a digitally designed platform that is easily upgraded and functions at higher frame rates than the older machine. It also incorporates numerous new modes including color Doppler, simultaneous 2D and M-mode or 2D and Doppler imaging, steerable Doppler, strain and strain-rate imaging, automated ventricular analysis8 contrast imaging and ECG / respiratory gated imaging optimization software. It has a tremendous advance over the older technology since it uses solid state linear array ultrasound probes as opposed to mechanical probes. This allows for an electronically controlled, dynamically focused ultrasound beam as opposed to the single focal point on the older ultrasound probes. Higher quality and easier image acquisition results, permitting a higher throughput during an imaging session. Imaging artifacts are also reduced with the new probes vs. the older system, since they do not require maintenance. Due to design limitations, the older machine operated with technology many decades old in comparison to modern clinical ultrasound machines. The new machine brings great advances and advantages for small animal imaging. The importance of this technology can be appreciated since transgenic and knockout mice are now used quite commonly to facilitate understanding the molecular basis of disease. Yet, imaging of the heart, vessel or other organs in embryonic or adult rodents has lagged behind these molecular advancements, thus hindering our ability to assess the physiological relevance of the genetic manipulations. The requested instrument will enable us to: 1) perform serial in vivo measurements in living rodents and 2) obtain real-time spatial resolution that is nearly microscopic. Non-invasive in vivo assessment of the function of the mouse heart has been difficult because of both its small size and also since it beats at >600 times per minute. The requested instrument, for the first time, enables accurate assessment of not only whole heart function, but regional wall motion. This advancement will have profound implications on understanding the physiological importance of genetic manipulations in rodents. The information gained from these studies will yield important and novel data which will advance our knowledge about the basis for a wide range of disease processes and potentially lead to future novel therapies. Further, the imaging platform requested will allow us to equip our trainees for the highly desired ability to perform integrative studies on animal models, a capability that will make them more competitive in the academic marketplace. PUBLIC HEALTH RELEVANCE: The proposed instrument will be used to visualize the cardiovascular system and other organs in animals ranging in size from the smallest mouse embryo, to the size of an adult rat or guinea pig. Using harmless ultrasound, akin to that used to visualize the developing human fetus, it will allow the investigators to measure a large array of anatomic and functional attributes in the living animal, even at multiple time points.